Importing from Jomsocial DB only

I have a jomsocial site that I am preparing to transition into ES but had a couple questions. Am I required to have a fully functioning Jomsocial site to import from or is it possible to do an import from a site that isn't running Jomsocial but has all database entries?

If so, can you list the database rows that are relevant to the import.
Also, if so, can the JS DB rows be dropped after the import or does ES use the same.
Finally, will the new beta version of ES 1.4 import videos from JS? (videos is what has held me back from transitioning)

Thanks